In a common commercial blueberry harvesting operation, the harvesters are mounted to relatively large farm tractors. Generally, a platform is provided on the back of the tractor to carry a number of empty blueberry containers and a number of full blueberry containers. The full blueberry containers are carried on the platform until most or all the blueberry containers are full. The harvester is then driven to the edge of a field where the containers are unloaded and transferred to a flat bed truck for example and carried to a warehouse or a processing plant.
Upon unloading the full blueberry containers to a shuttle truck, the harvester is reloaded with empty blueberry containers and harvesting is resumed.
For reference purposes, examples of blueberry and cranberry harvesters of the prior art are identified in the following publications:    U.S. Pat. No. 2,037,624 issued to H. J. Franklin on Apr. 14, 1936;    U.S. Pat. No. 2,795,099 issued to L. C. Getsinger on Jun. 11, 1957;    U.S. Pat. No. 3,616,630 issued to G. L. Gray et al. on Nov. 2, 1971;    U.S. Pat. No. 3,648,447 issued to C. G. Burton on Mar. 14, 1972;    U.S. Pat. No. 3,724,168 issued to H. W. Cassady Jr. et al. on Apr. 3, 1973;    U.S. Pat. No. 4,862,683 issued to R. D. Bragg et al. on Sep. 5, 1989;    U.S. Pat. No. 5,024,052 issued to R. D. Bragg et al. on Jun. 18, 1991;    U.S. Pat. No. 5,369,944 issued to O. Robichaud on Dec. 6, 1994;    U.S. Pat. No. 5,375,403 issued to G. E. Collins et al. on Dec. 27, 1994;    U.S. Pat. No. 6,000,203 issued to L. H. Weatherbee et al. on Dec. 14, 1999;    U.S. Pat. No. 7,716,909 issued to Dario Hebert on May 18, 2010;    CA Patent 1,249,727 issued to R. D. Bragg et al. on Feb. 7, 1989;    CA Patent 1,318,135 issued to R. D. Bragg et al. on May 25, 1993.
The blueberry picking device described in U.S. Pat. No. 7,716,909 issued to Dario Hebert herein above is particularly appropriate for mounting to the front end of a small tractor. It is appropriate for mounting to the front end of a small tractor of the type that is used on commercial lawn mowers and hobby farm equipment for examples. These small tractors have a capacity between 25 and 40 hp., and a weight of about 1600-1800 lbs.
For comparison, the older blueberry harvesters such as the ones described in U.S. Pat. No. 4,862,683; U.S. Pat. No. 5,369,944 and U.S. Pat. No. 6,000,203 for examples, are mounted to larger tractors which could weight between 2500-7,000 lbs and more. The footprint pressure of these large tractors is relatively high as they are made to travel on gravel roads, hay fields in dry season and forest floors. The tire threads on the large tractors are made for traction rather than low surface pressure. The tire threads are not made to be gentle to the plants and root systems on which they travel. The V-shape threads of a farm tractor wheel for example, has aggressive thread edges that can shear the root system of blueberry plants, just from the weight of the tractor itself. It is believed that such breakage of the root systems of blueberry plants can adversely affect crop during the next season. Although blueberry plants need pruning, it is believed that damage to the deep root systems and to the creeping stems (rhizome or surface roots) of blueberry plants should be avoided to maintain good plant production.
The operation of the large blueberry harvester requires a constant forward motion by the tractor. When one of the wheel encounters an obstruction, such as a bolder, more power is applied to the wheels from the engine's governor, so that the tractor can roll over that obstruction without faltering. Every time a large torque is applied to the wheel, the sharp V-threads of the wheels are susceptible of damaging the root systems and the surface stems (rhizomes) of some blueberry plants.
The Hebert blueberry picking head (U.S. Pat. No. 7,716,909) has opened an opportunity for harvesting blueberries using lighter machines. Moreover, the Hebert picking head is operated in a repetitive back and forth movement where excessive wheel torque on the tractor is never required. If an obstruction is encountered, the natural back-and-forth rocking motion of the machine can overcome it.
Also, the smaller and lighter tractors used to operate the Hebert picking head reduce soil compaction and create less plant damage in a blueberry field. The smaller lawn-type tractors mentioned above have a low footprint pressure, for being designed to operate on lawns and gardens that are watered and aerated on a regular basis. The tires on these tractors are relatively wider and the thread pads are large and closely spaced. Plant damage is reduced by both the tires profile and a lighter tire work due to the nature of the Hebert harvesting head.
The Hebert picking head has created an opportunity for a method for harvesting a blueberry field, without applying damaging pressure to the root systems of blueberry plants.
However, these smaller machines cannot carry as many blueberry containers as the larger tractors. This reduction in carrying capacity can represent an impediment to productivity if harvesting must be interrupted to transport each full berry container to an access road at the edge of a blueberry field.
Therefore, it is believed that there is a need in the blueberry farming industry for a new method for handling berry containers with the smaller machines such that the productivity of a picking head on a small tractor is comparable to the work of the larger harvesters on large farm tractors.